The present invention relates to a head supporting device for levitating type head, and a disk drive using the same such as a magnetic disk drive, optical disk drive, magneto-optic disk drive, and the like.
With reference to the accompanying drawing, described hereinafter pertains to a head supporting device of the prior art employed in a magnetic disk drive such as hard disk drive, as an example of the conventional head supporting device of a disk drive having a levitating type head.
FIG. 11 is a plan view showing a structure of a head supporting device of the prior art for a magnetic disk drive, and a relation between the head supporting device and a magnetic recording medium.
In FIG. 11, head supporting device 108 has such a structure that comprises suspension 102 of a comparatively low rigidity, plate spring 103, and support arm 104 of a comparatively high rigidity, and that the suspension 102 is provided with slider 101 having a magnetic head (not show in the drawing) mounted to an underside surface at one end thereof.
In addition, magnetic recording medium 107 is so disposed that it is spun by spindle motor 109. During writing and reading of the magnetic disk drive, the magnetic head mounted to the slider 101 receives a certain amount of levitation associated with a levitational force due to airflow generated by spinning of the magnetic recording medium and a thrusting force of the plate spring 103 which shifts the slider 101 toward the magnetic recording medium 107.
This structure of the head supporting device 108 is such that it rotates about bearing unit 105 by an interaction of voice coil 106 disposed to the support arm 104 during writing and/or reading, so that the magnetic head mounted to the slider 101 is positioned to a desired track on the magnetic recording medium 107 and performs the writing and/or reading.
The magnetic disk drive shown in FIG. 11 is a kind of magnetic disk drive, which is generally called a xe2x80x9ccontact start-stop modexe2x80x9d (hereinafter referred to as CSS mode), having a feature that the magnetic head mounted to the slider 101 levitates from the magnetic recording medium 107 during writing and/or reading, although it stays in contact with the magnetic recording medium 107 when the magnetic recording medium 107 is at a standstill.
In such a magnetic disk drive of the CSS mode, an area shown by a reference mark A of the magnetic recording medium 107 in FIG. 11 is the area that is magnetically writable, and another area shown by a reference mark B is the area where the magnetic head is retracted during a stop, which is called a CSS zone. When the magnetic recording medium 107 is to stop spinning, the magnetic head is first moved to the area B while it is kept levitated. When spinning speed of the magnetic recording medium 107 is reduced thereafter, the levitational force decreases as the airflow between the magnetic recording medium 107 and the slider 101 decreases. The magnetic head finally comes in contact with the magnetic recording medium 107, and it stops in that position.
Therefore, the magnetic recording medium 107 in the magnetic disk drive of the CSS mode is so formed that a surface of the area B is rougher than a surface of the area A, so as to prevent a problem that the magnetic head adheres to the magnetic recording medium 107 when coming to a stop, and damages the magnetic recording medium 107 mechanically and/or magnetically when it restarts again.
There are also other methods of the magnetic disk drive, of which one is a xe2x80x9cload/unload modexe2x80x9d (hereinafter referred to as L/UL mode).
FIG. 12 shows a general perspective view representing a structure of a magnetic disk drive of the L/UL mode. In FIG. 12, head supporting device 108 has a structure which is generally similar to that of the CSS mode shown in FIG. 11. However, the head supporting device 108 rotates about bearing unit 105, and moves outside of magnetic recording medium 107 when the magnetic disk drive comes to a stop. In this structure, there is provided ramp 110 at an outside of the magnetic recording medium 107, so as to prevent slider 101 and magnetic head from adhering to the magnetic recording medium 107 by letting the slider 101 supported on suspension 102 to ride up on a tapered portion provided on the ramp 110.
Referring now to FIG. 13, the structure and function of the conventional head supporting device will be described in more detail. FIG. 13 is a perspective view showing a main portion of the conventional head supporting device where a magnetic head is mounted.
The magnetic head (not shown in the figure) is mounted to a surface, which confronts magnetic recording medium 112, of the slider 101 disposed to an underside surface at one end of the suspension 102. The other end of the suspension 102 is bent, in a manner to function as plate spring 103, and this plate spring 103 is connected to the support arm 104. In the case of the CSS mode, the structure is such that the slider 101 is in contact with the magnetic recording medium 112 when the magnetic recording medium 112 is not spinning, and the slider 101 is thrust toward the magnetic recording medium 112 by a reactive force of the plate spring 103 against the magnetic recording medium 112.
As a design condition required for a head supporting device of the magnetic disk drive, it is necessary to impress a predetermined amount of load on the slider in a direction of the magnetic recording medium.
The purpose of this is to levitate the slider steadily and to stabilize an output of the magnetic head mounted to the slider even if there is any shock from the outside or a vertical movement of a surface of the magnetic recording medium during writing and/or reading.
Moreover, it is also necessary for the head supporting device to be such a structure that the plate spring has flexibility in order to maintain a steady thrusting force to the slider even when the surface of the magnetic recording medium is caused to make a vertical movement.
On the other hand, the head supporting device is required to have a high rigidity in order to prevent an impediment to trackability of the magnetic head mounted to the slider and to avoid an off-track error due to an undesired vibration mode that can occur in the head supporting device.
Furthermore, it is also necessary to form the head supporting device thin in a direction perpendicular to the surface of the magnetic recording medium in order to achieve miniaturization, or low-profiling to be more specific, of the magnetic disk drive.
However, because the conventional head supporting device has the structure in which the suspension and the support arm are connected with the plate spring, as described above, it is necessary to satisfy some conflicting conditions in order to meet a variety of requirements for the head supporting device.
In other words, it is necessary that the plate spring, to be more specific, has a reactive force large enough to impress upon the slider with a load it requires so that the slider carrying the magnetic head is levitated with stability. For this reason, number of attempts have been made to change an angle of bending (i.e. forming) between the suspension and the plate spring, and a material of the suspension, to adjust its thickness, and so on.
Next, it is also necessary for the head supporting device to have a certain degree of flexibility in order to prevent the load of the slider to the magnetic recording medium from fluctuating due to vertical movement of the magnetic recording medium, a manufacturing deviation in distance between the slider and the magnetic recording medium from one magnetic disk drive to another in the mass-production and the like. For this reason, the conventional head supporting device has been designed in such a way that the plate spring has the flexibility by providing it with cutout opening 111 as shown in FIG. 13, so as to lower rigidity of the plate spring and to reduce its spring constant.
Besides, if the suspension of a thin plate structure is adopted to increase the flexibility of the plate spring, it produces a vibrating mode such as twisting and the like during movement of the head supporting device for its positioning, because a frequency of its principal resonance point, or the resonance frequency becomes low. This causes the head supporting device to take some time to get itself settled (stabilized) from the vibrating mode, thereby placing a limitation on reduction of the access time.
In addition, since the conventional head supporting device has its center of gravity in a position nearer to the magnetic head than the plate spring, there occurs a phenomenon that the slider jumps off the magnetic recording medium, because the slider loses its balance between the levitational force of the airflow generated by spinning of the magnetic recording medium and the thrusting force placed by the head supporting device for shifting the slider toward the magnetic recording medium when a strong impact and the like is impressed upon the magnetic disk drive from the outside. Thus, possibilities exist that the slider hit the magnetic recording medium, and causes a magnetic damage and/or mechanical damage to the magnetic recording medium.
Although the load to be impressed on the slider is determined by forming of the plate spring, it is necessary to change the suspension according to the slider because the load can vary depending on a kind of the slider used.
Moreover, there has been no other means than discarding the suspension if the desired load could not be obtained due to a deviation in forming the plate spring. The reason of this is that a shape of the formed plate spring takes not only a part in simple adjustment of the load but also a greater part in resonance characteristic of the suspension. Therefore, it results in sacrifice of a resonance performance of the suspension when the load adjustment is made afterward.
The problems described above are not unique to the magnetic disk drive, but any other disk drives having levitating type head such as optical disk drives, magneto-optic disk drives, for instance, also have similar problems.
A head supporting device of the present invention comprises a support arm and a head mounted to an underside surface at one end of the support arm, wherein the support arm is disposed in a manner that it is rotatable about a bearing unit in a radial direction of a recording medium as well as a perpendicular direction with respect to a writing surface of the recording medium, and resilient means is provided for impressing upon the support arm with a thrusting force in a direction to the recording medium.
As a result, there is provided the head supporting device having an extremely high resistance to shock, high responsivity, and capability of making a high speed access, even if a shock is impressed from the outside, since a part constituting the support arm can be formed with the highly rigid material and the thrusting force of the resilient means to the slider can be set freely as desired, and also since the resonance frequency can be increased, because of the structure in which the part having a rigid body and the other part having resiliency can be provided independently with respect to each other.
In addition, the head can be held with a space away from the recording medium when the recording medium is at a standstill because of the structure in which the head supporting device is freely turnable in the perpendicular direction.
Further, the head supporting device of the present invention comprises the support arm and the head mounted to the underside surface at one end of the support arm, wherein the support arm is disposed in a rotatable manner about the bearing unit in the radial direction of the recording medium as well as the perpendicular direction to the writing surface, and resilient means is provided for impressing upon the support arm with a thrusting force in a direction to the recording medium. The head supporting device is also characterized by having a pivot pedestal disposed to the bearing unit so that a pair of bosses on the pivot pedestal abut upon the support arm, and thereby the support arm is disposed in a manner that it is rotatable in the direction perpendicular to the writing surface about points where the bosses of the pivot pedestal abut upon the support arm, as the points serve as a fulcrum.
Since this allows precise setting of a center of the rotation with a simple structure, it realizes positioning control of the head more accurately.
Furthermore, the pair of bosses provided on the pivot pedestal are so arranged that they abut upon the support arm on a phantom line that is perpendicular to both an axial direction of the bearing unit and a longitudinal direction of the support arm, and also traverses the rotational center of the bearing unit in the radial direction of the recording medium. Accordingly, there is provided the head supporting device that is well-balanced in weight along the longitudinal direction of the support arm while also superior in the resistance to shock.
Moreover, the bosses on the pivot pedestal are each arranged in positions that are symmetrical to each other with respect to a centerline along the longitudinal direction of the support arm. This can provide the head supporting device with a good balance in weight along a widthwise direction of the support arm and an outstanding resistance to shock.
Also, the head supporting device of the present invention comprises the support arm and the head mounted to the underside surface at one end of the support arm, wherein the support arm is disposed in a rotatable manner about the bearing unit in the radial direction of the recording medium as well as the perpendicular direction to the writing surface, and resilient means is provided for impressing upon the support arm with a thrusting force in a direction to the recording medium. The head supporting device is further characterized by having fixing means for securing the resilient means to the bearing unit, and adjusting means for adjusting a securing position of the resilient means to the bearing unit with the fixing means and for changing an amount of stress of the resilient means.
This can make the thrusting force of the slider to the magnetic disk medium freely adjustable, thereby making unnecessary an alteration of the head support mechanism even when a change is made in loading specification of the slider.
Further, the adjusting means comprises a spacer placed between the resilient means and the bearing unit. This can provide the head supporting device having the thrusting force adjustable with a simple structure.
Also, the resilient means can comprise a plate spring placed between the bearing unit and the support arm in the head supporting device of this invention. This can readily provide the head supporting device with a low profile structure in a direction perpendicular to the recording medium.
Furthermore, in the head supporting device of this invention, the head is retained by the slider mounted to the support arm, thereby realizing more precise levitation of the head by the design of an air streaming surface of the slider.
Moreover, a gimbals mechanism is disposed to the support arm for supporting the slider freely in a rolling direction as well as a pitching direction. The structure allows the gimbals mechanism to absorb an undesired tilt of the slider with respect to the recording medium in the rolling and the pitching directions during the operating.
In the head supporting device of this invention, a center of gravity of a portion held by the resilient means is in alignment with a point of intersection of a rotational axis of the support arm in the radial direction of the recording medium and another rotational axis in the direction perpendicular to the writing surface of the recording medium, so as to reduce undesired vibrations of the support arm to a minimum level possible even when there are any shocks and the like from the outside.
Next, a disk drive of this invention comprises a recording medium, a spinning means for spinning the recording medium, a support arm provided with a slider carrying a head on it, the slider mounted to one end of the support arm on a surface confronting a writing surface of the recording medium, the support arm being rotatable about a bearing unit in both a direction along the writing surface of the recording medium and another direction perpendicular to the writing surface, resilient means for providing the support arm with a thrusting force in a direction toward the recording medium, and driving means for rotating the support arm in the radial direction of the recording medium.
According to the structure as described above, a part constituting the support arm can be formed with a highly rigid material even if a shock is impressed from the outside, and the thrusting force of the resilient means to the slider can be set freely as desired. As a result, there can be provided the disk drive having an extremely high resistance to shock, as well as high responsivity and capability of making a high speed access since the resonance frequency can also be increased.
Furthermore, the disk drive of this invention comprises the recording medium, the spinning means for spinning the recording medium, the support arm provided with the slider carrying the head on it, the slider mounted to the one end of the support arm on the surface confronting the writing surface of the recording medium, the support arm being rotatable about the bearing unit in both the direction along the writing surface of the recording medium and the direction perpendicular to the writing surface, the resilient means for providing the support arm with the thrusting force in the direction toward the recording medium, and the driving means for rotating the support arm in the radial direction of the recording medium. In addition, the disk drive is characterized by further comprising a pivot pedestal having a pair of bosses and disposed to the bearing unit in a manner that they abut upon the support arm, wherein the support arm is disposed in a turnable manner in the direction perpendicular to the writing surface about points where the bosses of the pivot pedestal abut upon the support arm with the points serving as a fulcrum.
Accordingly, the structure as described makes possible precise setting of a center of the rotation with the simple structure, and thereby positioning control of the head can be realized more accurately.
Moreover, the pair of bosses provided on the pivot pedestal are so arranged that they abut against the support arm on a phantom line that is perpendicular to both an axial direction of the bearing unit and a longitudinal direction of the support arm, and also traverses a rotational center of the bearing unit in the radial direction of recording medium. Accordingly, there is provided the disk drive that is well-balanced in weight along the longitudinal direction of the support arm while also superior in the resistance to shock.
Also, the bosses on the pivot pedestal are each arranged in positions that are symmetrical to each other with respect to a centerline along the longitudinal direction of the support arm. This can provide the disk drive with a good balance in weight in a widthwise direction of the support arm and also an excellent resistance to shock.
Furthermore, the disk drive of this invention comprises the recording medium, the spinning means for spinning the recording medium, the support arm provided with the slider carrying the head on it, the slider mounted to the one end of the support arm on the surface confronting the writing surface of the recording medium, the support arm being rotatable about the bearing unit in both the direction along the writing surface of the recording medium and the direction perpendicular to the writing surface, the resilient means for providing the support arm with the thrusting force in the direction toward the recording medium, and the driving means for rotating the support arm in the radial direction of the recording medium. In addition, the disk drive is characterized by further comprising fixing means for securing the resilient means to the bearing unit, and adjusting means for adjusting a securing position of the resilient means to the bearing unit with the fixing means and for changing an amount of stress of the resilient means.
With this structure, the thrusting force of the slider to the recording medium is made freely adjustable, thereby making unnecessary an alteration of the head support mechanism even when a change is made in a loading specification of the slider.
In addition, the adjusting means comprises a spacer placed between the resilient means and the bearing unit. This can provide a disk drive having the thrusting force adjustable with a simple structure.
Furthermore, the disk drive of this invention comprises the recording medium, the spinning means for spinning the recording medium, the support arm provided with the slider carrying the head on it, the slider mounted to the one end of the support arm on the surface confronting the writing surface of the recording medium, the support arm being rotatable about the bearing unit in both the direction along the writing surface of the recording medium and the direction perpendicular to the writing surface, the resilient means for providing the support arm with the thrusting force in the direction toward the recording medium, and the driving means for rotating the support arm in the radial direction of the recording medium. The disk drive is characterized by further comprising depressing means for decreasing the thrusting force impressed upon the support arm by the resilient means when the support arm is turned to the radial direction of the recording medium and retracted to a predetermined area on the writing surface of the recording medium while the head is maintained in contact with the writing surface.
With this structure, in which the depressing means having a small spring constant comes in contact with and thrusts the other end of the support arm while the support arm is being turned in the radial direction of the recording medium, the head or the slider can be prevented from adhering to the recording medium. There is thus provided the disk drive which is small in size and thickness, high resistance to shock, excellent in portability, and capable of making a high speed access, with a simple structure while also achieving as much as possible a reduction of the load imposed during a start on a spindle motor serving the spinning means for the recording medium.
Further, the depressing means is characterized by being a plate spring disposed to the other end of the support arm for depressing the other end of the support arm when the head is being retracted, thereby realizing the structure capable of preventing the head or the slider from adhering to the recording medium with this simple structure and without using a separate driving source and the like.
In addition, the depressing means is so constructed that it decreases the thrusting force to an extent equal to or slightly smaller than that impressed upon the support arm, so as to realize the structure with the highest possible effect of preventing the head or the slider from adhering to the recording medium.
In the disk drive of this invention, the driving means comprises a voice coil disposed to the support arm, and use of its function enables the support arm to make even faster rotational movement.
Also, the resilient means comprises a plate spring placed between the bearing unit and the support arm in the disk drive of this invention. This can readily provide the disk drive with a thin structure in a direction perpendicular to the recording medium.
Furthermore, in the disk drive of this invention, a gimbals mechanism is disposed to the support arm for supporting the slider freely in a rolling direction as well as a pitching direction. This allows the gimbals mechanism to absorb an unwanted tilt of the slider in the rolling and the pitching directions with respect to the recording medium during writing and reading operations of a write/read device.
Moreover, in the disk drive of this invention, a center of gravity of a portion held by the resilient means is generally in alignment with a point of intersection between a rotational axis of the support arm in the radial direction of the recording medium and a rotational axis of the recording medium in the direction perpendicular to the writing surface of the recording medium. This can reduce undesired vibrations of the support arm to a minimum level possible even when there are any shocks and the like from the outside.